Radio tuning device



Aug. 17, 1937. A. A. THOMAS 2,090,315

RADIO TUNING DEVICE Filed July 30, 1929 4 Sheets-Shet 1 a o 5 a 5 a4.4%@ f Aug. 17,` 1937. A. A. THMAS 2,090,315

RADIO TUNING DEVICE Filed July 50, 1929 4 Sheets-Sheet 2 INVENTOR Aug.17, 1937. A. A. THOMAS RADIO TUNING DEVICE Filed July 3o, 1929 4Sheets-Sheet 5 Aug. 17, 1937. A.l A. THOMAS RADIO TUNING DEVICE FiledJuly 30, 1929 4 Sheets-Sheet 4 INVENTOR Patented Aug. 17, 1937 UNITEDSTATES PATENT OFFICE RADIO TUNING DEVICE Application `luly 30, 1929,Serial No. 382,117

13 Claims.

My invention relates to radio receivers, and its object is to provide asimple and reliable device for `controlling the tuning shaft from adistance tc bring in a desired station. The main purpose of thisinvention is to produce a remote tuner of compact structure with as fewparts as possible, so that it can be applied to any type or make ofreceiver at little cost.

According to my invention, the tuning shaft of a receiver is driven by asmall electric motor though an automatic reversing connection whichmoves the shaft slowly back and forth over the indicator range. A set ofcams or other form of switch-operating members on the tuning shaftrepresents a number of selected broadcasting stations, and each camautomatically closes a switch when the corresponding station is in tune.A small box or casing located at a distance from the receiver' containsa set of keys Aor buttons which represent the selected stations referredto. A cable carrying the necessary wiring operatively connects thecontrol box with the receiver. When a key is depressed, the motorcircuit is closed and the tuning shaft is turned until the switchcorresponding to the actuated key is closed by the associated cam,whereupon an electromagnet is energized to open the motor circuit. Theradio shaft is almost instantly stopped in tuning position for thedesired station. A lamp in the control box automatically goes on whenthe station is in tune, and the turning of a knob gives the requiredvolume. The switchecperating cams may be individually adjustable for anystation.

In a preferred embodiment of my invention, the control box carries anextra key for tuning in any station on the dial. When this key isactuated, the motor circuit is closed and remains so as long as the keyis held down. In other words, the tuning shaft moves over thebroadcasting range until the operator gets the program he wants. Then hesimply releases the key and the selected station remains in tune becausethe motor circuit is open. When this manual tuning key is used, theautomatic tuning switches controlled by the other keys are idle.

Another important feature of my new remote tuner comprises means forkeeping the loudspeaker silent until the selected station is brought in.This prevents unnecessary noises, frequently disagreeable, during theprocess of tuning, and it is only when the wanted station is in tunethat the loudspeaker is automatically turned on. This silent tuningapplies only to the automatic keys that bring in certain preselectedstations. When the manual tuning key is actuated, the

(CI. Z50- 20) loudspeaker circuit remains closed so that the operatorcan hear each broadcast program and make his selection.

As evidence of the simplicity of my remote tuner, I may point out thatonly two electromagnets are needed for all the control circuits. If thesilent tuning feature is not desired, only one electromagnet isnecessary. The switch mechanism in the control box is exceedinglysimple, comprising only a number of key-actuated spring blades which mayconveniently be arranged in radial fashion. There are no electromagnetsin this box, which can therefore be made unusually small, flat andlight, for placing in almost any spot. It can be put on a desk or table,or on the arm of a chair; it can be held in the lap or taken to bed. Theoperation oi" the control box is so simple that a child can use it.

The practical advantages and novel features of my invention will beunderstood from a detailed description of the accompanying drawings, inwhich- Fig. l shows a circular form of my new control box in top view;

Fig. 2 is a cross-section on line 2-2 of Fig. l;

Fig. 3 illustrates a plan view on section line 3 3 of Fig. 2;

Fig. 3a represents a fragmentary section on line SLL-3a of Fig. 2 toshow the common cone nector for the radial switch arms;

Fig. 4 is a fragmentary sectional view on line 4-4 of Fig. l, showingthe manual tuning key and associated switches;

Fig. 4a is an enlarged section on line fla-4a of Fig. 4;

Fig. 5 shows a front view of the driving connections and switchmechanism associated with the tuning shaft of the radio receiver,certain parts being sectioned for clearness;

Fig. 6 is a side View of Fig. 5, looking from right to left;

Fig. 'l represents a plan view of the apparatus shown in Figs. 5 and 6;

Fig. 8 is a detached side View of one of the cam disks on the tuningshaft in switch-closing position;

Fig. 9 shows the two electromagnets of the tuning system and theirassociated switches for controlling the motor circuit and theloudspeaker circuit; and

Fig. l0 is a diagram of circuit connections between the remote controlbox and the operating mechanism of the tuning shaft.

Referring to the first sheet of the drawings, which show the remotecontrol box, there is an from five or six stations.

outer casing Il! provided with a removable bottom I2 attached in anypractical way, as by screws I3. The parts III and I2 are preferably madeof insulating material of the bakelite type, and the box as a whole iscolored and ornamented to suit the taste of the manufacturer. The top ofthe box is here shown integral with the body, but it may obviously be aseparate plate, in which case the bottom I2 may be molded or castintegral with the body of the box. It is convenient to make the box ofcylindrical shape, which adds to its compactness and pleasingappearance, but any other practical'shape may be used.

The bottom plate I2 is provided at the center with an upstandingcylindrical support I4, which is preferably formed as an integralprojection. The insulating support I4 carries three sets of spring armsI5, I5 and Il, each set in this instance comprising ve arms. |Thisnumber, however, is merely arbitrary, for it has been assumed that thepresent embodiment of the invention is capable of automatically tuningin ve stations. Manifestly, the number of stations to be handled b-y thetuning box depends upon the manufacturer, but under our present systemof chain broadcasting there is hardly any locality that can not get allthe best programs As shown in Fig. 2, the switch arms I5, I5 and Il arespaced by insulating blocks I8 and I9, which are secured to thecylindrical support III by bolts or screws 25. rThe spacing blocks I8and I9 may be in the form of arcuate strips of bakelite or similar l.material, and are in eifect separable sections of thecylindrical'support I4. There is no harm -if the heads of bolts are incontact with the upper spring arms I5, because the bolts are fullyinsulated from switch arms I6 and I'l. If desired, the heads of bolts 2Umay be used as binding posts for connecting the switch arms I5 incircuit. Each aligned pair of switch arms I5 and Il is mechanicallyconnected 'by an insulating pin or lug 2l, which may be attached toeither arm.

The switch arms I5, IS and I1 areA actuated by suitable keys or buttons22 extending through slots 23 in the top of the box. The key stems 2liare secured in any practical way to the free ends of switch arms I5. Theheads of keys 22 are attached to the stems 2li after the bottom plate I2has been xed in place and the key stems project through 'slots 23. Anordinary screw-threaded connection 25 may be used to mount the key headson stems 24. In Fig. 1, the keys 22 are dierentiated by the letters A toE, which are supposed to represent ve selected stations. ln other words,when a person wants station A, he simply pushes down key A; when stationD is desired, key D is pushed down; and so on. When a keyl 22 isactuated, the connected switch arm I5 is forced into contact with switcharm I5, and switch arm Il is moved into contact with a circularconducting bar or strip 25, which is common to all switch arms I'I. Itis clear from Fig. 2 that switch arms I5 and I6 are closed beforeswitcharm I'I strikes the contact bar 25. When the actuated key is released,the switch arm Il leaves the contact bar 2B before the switch arms I5and I6 separate. I The reason for this relative timing of the switcheswill be explained in connection with the circuit diagram of Fig. l0. Theswitch arms I5, I6 and Il are preferably in the `form of spring blades vwith just enough resiliency-to permit-'operation of keys 22 by easypressure, so that even a child can use the control box. II'he inherentresiliency of the spring blades I5, I5 and I'I causes them to returninstantly to normal open position when the keys are released. 5

An extra key 2l, which call the manual tuning key, is for the purpose ofoperating the tuning shaft to sweep the indicator dial from one end tothe other until the desired program or station is found. In other words,key 2l is ac- 10 tuated when it is desired to tune in any station notrepresented by keys A-E, which bring in only certain preselectedstations. The shank 24 of key 21 is connected to the free end of aswitch arm 28, which is secured at its inner end to the l5 circularsupport Il by a screw or bolt 29. Below the switch arm 28 are two switcharms 3B and 3|, which are mounted on support III by means of aninsulating block 32. A metallic pin or lug 33 fixed on the free end ofarm 28 is adapted 2O to engage switch arm 3B when key 2l is pushed down.An insulated contact piece 36 connected to spring arm 28 engages switcharm 3l when arm 28 is forced down by key 2l. The arrangement of contactpieces 33 and 34 is such that, 125 when key 2l is depressed, the contactpiece 33 strikes switch arm 32 before the contact piece 34 strikesswitch arm 3l. This insures the positive closing of the two switches. Astop on the bottom plate I2 limits the downward move-@i3n ment of key2l. The head of key 2l may be colored differently from the heads of theautomatic tuning keys 22, and all key heads are preferably molded ofbakelite or similar insulating material. 535

The three switch arms 2li, 3@ and 3l are spring blades of goodconducting material and having the right amount of resiliency, asexplained in connection with switch arms I5, Ie and Il'. The two springblades 35 and 3l are in eifect a single switch member, for they arealways in metallic contact with each other. The onlyreason for usingltwo switch arms is to insure arm closure of both contact pieces 33 and32 when the key is pushed down. Any other practical switch constructionmay be used with key 2l. The insulated contact piece 34 acts as aterminal for a circuit conductor 36. A conductor 3l is connected toswitch arm 28, and for this purpose the bolt or screw 29 may be used asa binding post. The.; switch arms 3U and 3l are connected in circuitthrough a conductor 38 which is common to both.

A knob or other suitable linger piece 39 arranged centrally on top ofbox Ill is adapted to control a Volume regulator f-I, which may be aresistance or any other suitable device adapted to increase and decreasethe loudspeaker volurne when knob 39 turned. As. volume-controllingdevices for radio receivers are well known, I need not show or describeany details of part. 40, which may conveniently be mounted in thecylindrical support III. A suitable switch 4I permits the radio set tobe turned on and oi at will. The switch tII may be of the weil knowntoggle type, which has a' pivoted nger piece that is easily snapped fromone position to the other. The control box I0 may also be provided witha small signal lamp i2 screwed into a metal socket 43 and covered by alens Il of suitably colored glass or other transparent material. Thelamp socket d3 is screwed into an opening I5 in the top of box I andconstitutes one terminal of the lamp circuit. The lens le is xed in lacap e5, which has a cylindrical flange Il adapted to fit tight over asimilar ilange l5 of socket 45. This simple mounting permits easyremoval' of cap 46 for access to lamp 42. The central terminal of lamp42 is in contact with a spring arm 49 which is secured to support |4 byscrew 5D or otherwise. An opening in the side of box I allows theinsertion of a cable which carries all necessary circuit conductors foroperatively connecting the remote control box |0 with'the radioreceiver. In a simpler form of my invention, the signal lamp 42 may beomitted, but it adds to the attractiveness and utility of the controlbox by flashing a signal when the desired station is in tune. The radialarrangement of the switches controlled by keys 22 and 21 reduces thedimensions of box |0 to a minimum. In actual size the box need not belarger than shown in the drawings and may even be smaller.

The second and third sheets of the drawings show the mechanism in theradio receiver controlled by the switches in box I0. The tuning shaft 52of any selected make or type of radio receiver is rotatably mounted inbearings 52 and 53. In this instance the tuning shaft runs length- Wiseof the cabinet parallel with the front panel 55, but this particulararrangement is not necessary, for sometimes the tuning shaft of a receiver runs from front to rear of the cabinet. The bearing 54 is part of abracket 56 secured to the front panel 55 by bolts or screws 51. A baseplate 58 secured by bolts 59 to the bottom board 60 of the radiocompartment carries an upright post or standard 6| which terminates atthe top in a cross arm 62. A lateral extension 93 on post 5| carries apin 64 on which a rocking lever 65 is pivoted. The front end of lever 65is in the form of (or otherwise carries) a segmental gear 66, which ispermanently in mesh with a pinion or gear wheel 61 xed on the tuningshaft 52. A rotary cam cylinder 88 is mounted on a shaft 69 between baseplate 58 and cross arm 62. The lower end of shaft 59 is suitablysupported in a bearing 70 on base plate 68 for rotation with minimumfriction, while the upper end of this shaft is journalled in the crossarm 62 of standard 6|. The rotary cylinder 68 is provided with a camgroove which runs around the cylinder from top to bottom and back againin a continuous curve. A roller 'l2 on the rear end of lever 63 rides incam groove It is clear from Figs. 5 and 6 that the rotation of cylinder68 in the same direction produces a rocking or oscillatory motion oflever 55, whereby the tuning shaft 52 is rotated back and forth througha predetermined arc to cover the entire broadcasting range. In mosttypes of radio receivers on the market, the range of the stationindicator covers a half revolution of the tuning shaft. It may thereforebe assumed that for every half revolution of cylinder 68, the tuningshaft 52 is moved from one end of the indicator to the other. In theposition of the parts as shown in Figs. 5 and 6, the tuning shaft isabout midway on the indicator. It is thus clear that for everyrevolution of the cam cylinder 68, the lever 63 is rocked clockwise andcounterclockwise to actuate the tuning shaft from one end of theindicator to the other and back again. The cam cylinder 68 is rotatedcontinuously in the same direction at properly reduced speed by a smallelectric motor |3, which has a shaft 14 carrying a worm |5 in mesh witha worm gear 16 fixed on shaft 69 of cylinder 68. The speed reductionbetween the motor shaft 14 and tuning shaft 52 is preferably such thatthe latter is operated at about the speed used in hand tuning.

A solenoid coil '|I is fixed in upright position on the bottom board 50by an insulating cap l" or in any other practical way. A magnetic coreor plunger '|9 is movable axially in the central opening of the coil.The extension I9 of plunger 19 carries an insulating head 89 attached tothe free end of a spring blade 8|, which is mounted on an upright post82. A lateral extension 93 of post 82 carries a spring arm 94, which isslotted to receive the extension 'i9' of plunger i9. A Cotter pin 85passing through extension I9 and lying over the spring blade 84 connectsthe latter to the plunger for downward movement. The supporting standard82, which is secured to the bottom board 69 by screws 85 or otherwise,is`

preferably of insulating material, but it may also be a metal casting orof sheet metal, except that then the switch arms 8| and 84 must beinsulated from each other. The normal resiliency or set of spring arms8| and 84 is such that the free end of arm 8| is normally pressedagainst a contact 8'! mounted on an arm 88 of insulating bracket 89.

The front panel 55 carries a horizontal bracket 98 to which the bracket69 is secured by bolts or rivets 9|. It is possible, of course, to makethe brackets 89 and 99 as a single member of bakelite, aluminum, orother suitable material. An arm 92 at the lower end of bracket 89carries a spring arm 93 normally in pressure contact with a terminal 94mounted on arm 88. The terminal 94 may simply be the head of a bolt 95secured by the usual nut. A spring arm 96 is secured at its upper endbetween the brackets 89 and 99 by rivets 9| and terminates at its lowerend in a hook or catch 9'! arranged to be engaged by the free end ofswitch arm 84. A coil 98 surrounding a magnetic core 99 is supported inhorizontal position from the front panel 55 by means of an insulatingcap or shell |58. An armature |9| xed on spring arm 96 is attracted tothe pole of core 99 when coil 98 is energized. When this happens, thecatch 91 at the end of arm 95 is moved out of the path of switch arm 84.An insulating block |02 on front panel 55 carries a spring arm |03arranged to be engaged by spring arm 84 when the latter is moved downinto the dotted line position 84. It goes without saying that theterminals or contact members 87, 93 and 94 are insulated from eachother, either by the insulating material of bracket 89, or (if thelatter is of metal) by separate insulation.

The operation of the switch mechanism shown in Fig. 9 is as follows: Inthe normal position of the parts, the spring arms 8| and 84 hold thesolenoid plunger 19 up, with the arm 8| pressing firmly against contact8l. The free end of switch arm 84 is above catch 91 of spring arm 95,and the switch contacts 93-94 are closed by the normal tension of springarm 93. When the coil l1 is energized, the magnetic core or plunger 'I9is instantly pulled down against the tension of the supporting springblades 8| and 84, and the following operations take place: Switch arm 8|breaks contact with terminal 87, switch arm 93 is forced away fromterminal 94 by the lateral ex-A tension 80' of head 89, and switch arm84 is moved into pressure contact with switch arm |93. During thedownward movement of switch arm 84, the bevelled catch 91 is pushed tothe left and then snaps back again to lock the switch arm 84 in closingposition 84. The extension |9 of plunger 19 slides freely in the slot ofswitch arm 84, so that the plunger is free to return to normal positionwhile the switch arm 84 remains locked.

When coil 98 is energized, the magnetic attrac- 75 tion betweenparts 99and IGI movesvthe spring arm QB to the left and thereby withdraws thecatch 9i from switch arm Sill,V so that the latter instantly rises tonormal position by its inherent tension. This takes place only when theplunger 'i9 is in normal raised position, s o that the crosspin 85 doesnot interfere with the return of switch arm Bil.

The tuning shaft 52 carries condensers or other tuning elements it andan indicating drum |05. These parts may be of any approved constructionand are so well understood that they require no further description. Themovements of shaft 52 for automatic tuning are controlled by a series ofdisks l' secured on the shaft in properly spaced relation. In thepresent instance there are live disks, because it has been assumed thatfive stations are automatically tuned in by the remote control box ifi,as previously explained. Sincethese disks are alike in structure, adescription of one will suffice for all. Referring to Fig. 5, where oneof the disks is shown in section, it will be seen that each disk has abody portion lill provided with a hub lila for receiving a pin illewhich passes through shaft 52. The hubs i598 also serve as automaticspacing means for the disks when they are strung on the shaft. The bodyportion iii'l carries a lring llt, which is radially adjustable andfixed in position by one or more set screws l i2. Each ring lill isprovided with a cam H3, which may be formed integral with the ring orattached thereto as a separate piece. The cams H3 of the different disksare arranged in predetermined angular relation, as shown in Fig. 6. Theposition of each cam H3 determines the position in which the tuningshaft 5:2 is stopped, as will presently become clear. The body portionlill and ring section l lil of each disk lili may be cast of aluminum orother light metal, or they may be molded from composition material ofthe bakelite type. No particular construction of cam disk is necessaryand an ordinary disk may be used without the adjustable ring IIB. Thelatter, however, serves the practical purpose of permitting radialadjustment of cam H3 to change from one station to another. The radialpositions of the iive cams M3 in Fig.' 6 are intended to correspond tothe live stations represented by keys A-E of the control box l.

Two spaced brackets l lil projecting rearwardly from the front panel 55carry a rod H5 which supports a series of switch arms H5 arranged inalignment with the cam disks ilil. The switch arms H6 may be in the formof spring blades bent at l il around the common supporting shaft H5.Sleeves H8 on shaft liti hold the switch arms il@ in properly spacedrelation. Since the switch arms il@ are. connected to a common terminal,the-rod 95 is'preferably of brass, or other good conducting metal, andissuitably insulated. Each switch arml l@ is offset to form a rounded orbevelled cam M9, 'which normally rides over the smooth periphery of theassociated disk, as shown in Fig. 6. yThe front panel 55 supports aninsulating bar |29 which carries a series of contacts |26. Thesecontacts may be in the form of bolts, which are easily secured to thesupporting bar d20 by nuts |22. The insulated contacts l2l are in linewith the free ends of switch arms H6. As long as the switch arms l Itride over the circular periphery of the. associated disks leb, the freeends of the arms remain out of engagement with contacts |2l (see Fig.6). However, when the cam ||3- of any diskrencounters the, cam H9A ofthe associated switch arm l|f,`as' shown in Fig. 8,

`the free end of the arm is moved `into pressure engagement with theadjacent Contactv l2l.

In the circuit diagram of Fig. l0, the various switch 4arms and.contacts associated with keys A-E and cam disks ||l| are distinguishedby means of sufx letters age, so as to facilitate the tracing of thecircuits for .the different keys. The common connection between switcharms l@ is indicated by a conductor |23, which is connected at |2l tothe main circuit lead i225 of a suitable plug |25 adapted to beinsertedin a house-lighting socket. The other lead lill includes the on-and-offswitch Lil, previously referred to. A wire |28 connects thecommoncontact bar 26 to conductor 38, which is shown as an extension ofconductor |25. The live switch arms H6 are connected in parallel to acommon conductor |29, which leads to one side of coil ll.

The other side of this coil is connected to conductor lill. The signallamp 52 is included in conductor |29 and is preferablyy shunted by aresistance l, so that the system will not be disorganized if vthe lampshould burn out or be removed. The switch arms |511, to Llc areconnected to the corresponding contacts l2 la to l2 le by conductors|3|a to |316, respectively. The switch arms Ha. to lle are connected toacommon conductor |32, which leads to switch contact 2l. The switcharm'l is connected by wire |33 to the motor terminal ,i3-4i, to whichthe conductor 3l is also connected. A wire 35 connects the other motorterminal |35 to the circuit lead Ml. The switch members 85 land w3 areconnected by wires lil and |38 in the operating circuit of a loudspeakerdiagrammatically indicated by the outlines |39. This loudspeaker, whichmay be of any approved type, is supposed to be connected in the outputcircuit of the radio receiver through transformer |49, or in any other'practical way. As long as switch lill-m3 is open, the loudspeaker |39 isinoperative.

Let us suppose that key A is depressed to tune in station A. The circuitof motor l is closed as follows, it being assumed that switchilllremains closed: circuit main |41, wire E35, electric` motor T3, wire|33, closed switch contacts l-Sl, conductor |32, switch arm Ila, contactbar 253, wire |28 and return lead |25. The energizedmotor drives thetuning shaft 52through the auto"l matic reversing connection previouslydescribed until cam ||3 of disk |060, strikes cam H9 of switcharm ||6aand moves the same against contact |2|a. j This energizes coil ilthrough the following circuit: main conductor |41, coil "ll, conductor|29 (including signal lamp `d2), closed switch members ||6a-|2|a, wire|3la..closed switch contacts IEa-l'a, and through conductor |23 toreturn main |25 of plug H25. The energized coil 'l1 instantly pulls downthe magnetic" to spring back to normal closing position. This,l

however, does not close the motor circuit, because the .switch arm llais openedV before the solenoid circuit is interrupted by the separationof contacts lila-Ita. If necessary, abrake may be As soon las theoperator used to accelerate the stopping of motor shaft 14.

When any one of the other keys B-E is actuated to bring in the desiredstation, the circuits of motor 13 and coil ''l are closed in the sameway through the switches controlled by the actuated key and itscorresponding cam disk. This is clear from Fig. l0 without the need oftracing each circuit in detail. Ther-e is, however, one operation thatrequires special notice. Since the loudspeaker switch Z4-|93 remainsclosed after the release of an actuated key, it is necessary to openthis switch when the next key is d-epressed so as to keep theloudspeaker out of circuit until the next tuning position of shaft 52 isreached. The opening of loudspeaker switch 84|03 is automaticallyaccomplished in the following manner. Let us assume that key B isactuated to bring in station B. The circuits of motor 13 and solenoidcoil 11 we need not trace, because they will be understood from what hasbeen said before. When key B is pushed down, coil 98 is energizedthrough the following connections: conductors |47 and |48, closed switchcontacts Sli- 93, coil 98, conductor |32, switch arm l'lb, Contact bar26, conductor |28, and the other side |25 of the work circuit. Theenergized electroinagnet 98-99 attracts armature IUI and moves thespring arm 95 away from switch arm 84, which instantly springs up toopen position. This opening of the previously closed loudspeaker switch84| |13 takes place as soon as any key is depressed, so that theloudspeaker is silent until the shaft 52 is again in the desired tuningposition. The closing of switches 8|-81 and 93-94 when coil 'l1 iscle-energized is subsequent to the opening of switch ||-26, so thatneither the motor circuit nor the circuit of coil 98 is closed byrelease of the actuated key.

I explained briefly in connection with Fig. 1 that the separate key 2'!was for the purpose of tuning in any station independently of 'keys A-E.The circuit diagram of Fig. l0 indicates how that is done. When key 2Tis pushed down, the circuit of motor i3 is closed as follows: conductors|41 and |35, motor i3, wire 31, closed switch arms 28 and 30, conductors38 and |25. The motor circuit is therefore closed independently of keysA-E and cam disks |85, so that the motor keeps running as long as key 21is held down. As soon as the operator hears the desired program, hesimply releases the key and the motor stops, leaving shaft 52 in tuningposition for the desired station. During the operation of tuning shaft52 by means of key 2l, it is necessary to keep the loudspeaker circuitclosed, because the operator is on a fishing expedition, as it were, andwants to hear all the programs that are on the air, so that he can makehis selection. When key 27 is pushed down, the circuit of solenoid coilTl is closed through the following connections: conductor It?, coil l1,conductor 3E, closed switch 34-3|, and conductor 3B to the other side ofth-e work circuit. When coil 'il is energized, the plunger 1B is pulleddown to close the loudspeaker switch Bftm3, as previously explained.This switch remains closed not only as long as key 2l is held down, buteven after the key is released. The only time that the closed switchSII-|03 is opened, is when an automatic tuning key A-E is actuated, aspreviously explained.

It is clear from the preceding description that I have provided a remoteautomatic tuning system of simple construction and reliable operation.The cam disks |55 are easily adjustable for any desired station, so thata manufacturer can readily adjust this automatic tuner for the mostdesirable stations in any particular locality of the country. Thischange of stations may also be made by the owner of the set, since it isan exceedingly simple matter. The manual tuning key 21 supplements theautomatic tuning keys, in that it permits a person to tune the receiverat a distance for any station that happens to be broadcasting. Not theleast important feature of this automatic tuning system is the fact thatthe loudspeaker remains silent until the selected station is in tune.

Although I have shown and described certain specic constructions andcircuit arrangements, I want it understood that my invention is notlimited to the details set forth. Changes and modifications will perhapsoccur to others, without departing from the scope of the invention asdefined in the appended claims. I have used the word key in the claimsas a convenient term to indicate any suitable hand member foroperatating the switches in the control box. When I speak of the shaft52 as a tuning shaft, I do not mean that the tuning elements must bemounted on the shaft, but I include any shaft whose operation controlsthe position or condition of the tuning elements in the receiver.

I claim as my invention:

1. In a radio receiver, the combination of adjustable tuning elements, aset of individually operable members representing each a certainstation, mechanism controlled by said members for adjusting saidelements in accordance with an actuated member, a loudspeaker, meanscontrolled by said members for disabling the loudspeaker during thetuning operation, a separate finger piece operatively connected withsaid mechanism for tuning in any desired station independently of saidmembers, and means controlled by said finger piece for maintaining theloudspeaker active during the tuning operation effected by said fingerpiece.

2. The combination of a shaft, an electric motor for operating the same,a set of normally open switches comprising each a movable arm, saidswitches being connected in parallel, means operated by said shaft formoving said switch arms to closed position, each switch arm being closedonly when the shaft is in a certain position predetermined which isdifferent for each arm, a second set of normally open switches connectedin parallel to each other and in series with said rst set of switches, athird set of normally open switches connected in parallel to each otherand included in the circuit of said motor, a normally closed switch inthe motor circuit in series with said third set of switches, a set ofindividually operable keys for controlling the second and third set ofswitches, whereby the actuation of any key closes the motor circuituntil said shaft-operated means closes the particular switch arm thatcorresponds to the actuated key, means whereby each key automaticallyreturns to normal position when released, and electromagnetic meansadapted to be energized by the closing of any switch arm to open saidnormally closed switch and stop the motor.

3. In a radio receiver having a loudspeaker circuit, mechanism fortuning the receiver to any desired station, said mechanism including anelectric motor, a normally closed switch in the motor circuit, anormally open switch in the loudspeaker circuit, each of said switchesincluding a movable contact arm, a common actuating member connected toboth arms and normally held in position to keep the first switch neticmeans for operating said member to actuate both arms simultaneously,whereby the rst'switch is opened and the second switch isclosed, andmeans for releasably locking the arm of the loudspeaker switch in closedposition without interfering with the return of said member to no-rmalposition.

4. The combination of a radio tuning shaft, an electric motor foroperating the same; an electromagnet, means for automatically energizingsaid electromagnet when said shaft is in any one of a plurality ofselected tuning positions, manually controlled means for selecting theparticular tuning position of the sha-ft at which said electromagnet isenergized, means for breaking the motor circuit and stopping the shaftwhen said electromagnet is energized, a normally open switch in theloudspeaker circuit, means for automatically closing said switch whenlsaid electromagnet is energized, whereby the loudspeaker operates onlywhen the shaft is in selected tuning position, means for automaticallylocking said loudspeaker switch in closed position when saidelectromagnet is ycle-energized, and manually controlled electromagneticmeans for releasing said locking means.

5. The combination of arotary shaft carrying a cam, an electric motorfor `operating said' shaft, a normally open switch comprising a movablearm arranged to be closed bysaid cam when the shaft is inpredeterminedposition, a manually operable switch normally open andconnected in series: with said'frst named switch, a

second manually operable switch normally open and connected in the motorcircuit, a single movable nger piece for closing both of said :manualswitches, said linger piece returningv automatically to normal positionwhen released-by the operator, a normally closed electromagnetic switchin the motor circuit in series with the second manual switch, andcircuit connections whereby said electromagnetic switch is energized andthereby opened to breaky the motor circuit whenithe first named switchis closed.

6. The combination of a shaft'rotatable in opposite directions through apredetermined arc, a single electric motor for operating said shaft,means for automatically reversing said shaft at each end of its arc oftravel, a normally closed switch in the motor circuit, anelectromagnetadapted to open said switch when energized, a plurality of parallelcircuits for saidelectromagnet, a pair of normally open .switchesconnected in series in each ofsaid circuits,- a set of manually operablekeys for selectively closing one switch in any pair of said switches,said keys automatically returning to normal position when manuallyreleased,v means controlled by said shaft for closing the other switchof each pair when the shaft is fin'y predetermined position, the closingof any pairof said series switches causing said electromagnet to beenergized and open the motor circuit, a single separate key operableindependently of said set of keys, and anormally open switch closed bysaid separate key Vto energize the motor and operate said shaft ineither direction as long as `'said key is held down, the manual releaseof said key instantly breaking the motor circuit and stopping the shaft,said automatic shaftreversing means causingv the lshaft to oscillatethrough its'predetermined arc aszlong as said key is held down.

7. A radio receiver having an adjustable tuning shaft and a loudspeakercircuit, an electric motor for operating said shaft, a normally closedswitch in the motor circuit, a normally open switch in the loudspeakercircuit, a set of manually operable keys representing each a selectedstation, circuit connections controlled jointly by said shaft and anyactuated key for automatically opening theY motor switch and closing theloudspeaker switch when the shaft is in tuning position for the stationrepresented by the actuated key, means for automatically locking theloudspeaker switch in closed position, and means operated by theactuation of the next key for releasing said locking means to permitopening of the loudspeaker switch until the next selected station is intune.

8. The combination of a rotary shaft, an electric motor for operatingsaid shaft, a normally closed switch in the motor circuit, a set ofnormally open switches connected in parallel in the motor circuit and inseries with said normally closed switch, manually operable keys` forclosing any one of said parallel switches, each key representing acertain angularposition of the shaft, a second set ofnormally openswitches representing-the same shaft positions as said keys, meansmovable with the shaft for closing said last mentioned switches when theshaft is in predetermined position as represented by the actuated key,connections for closingl the motor circuit when a key-operated'switch isclosed, and electromagnetic means for automatically opening saidnormally closed motor switch upon the closing of the shaft-operatedswitch that corresponds to thekey-operated switch.

9. In radio tuning apparatus, the vcombination of a remote control boxhaving a set of manually operable keys representing each a selectedstation and having one extra keyfor tuning in any station, a radioreceiver having a rotary tuning shaft, an electric motor foroperating-said shaft, a loudspeaker circuit, electric mechanismcontrolled by each key for energizing said motor to operate the shaftand automatically de-energizing the motor to stop the shaft in tuningposition for the station represented by the actuated selecting key,electric connections controlled by said extra key for closing the motorcircuit and operating said shaft as long as Athe keyis held down,` aswitch for holding the loudspeaker-circuit inoperative during rotationof said shaft when a station-selecting key is actuated, means-forautomatically operating said switch to render the loudspeaker circuitoperative when the shaft stops in tuning position for the stationrepresented-by the actuated selecting key, and means for causing saidswitch to hold the loudspeaker circuit operative while the tuning shaftis lunder the control of said extra key.

10. The combination of a radio tuning shaft,

an electric motor for operatingsaid shaft, a set of'manually operablelmembers representing each a certainstation, electrical connectionscontrolled by anyactuated member to energize said motor and rotate theshaft until the station corresponding to that member is in tune, alinger piece manually operable independently of said members,switchmeans controlled by saidnger piece for Yenergizing the motorcircuit and operating said shaft as long as the finger piece is held inoperative position, a loudspeaker circuit which remains disabled duringthe Operation of said shaft under the control of any one of saidmembers, electrical connections for automatically rendering theloudspeaker circuit operative when the shaft reaches a preselectedtuning position,

and means for maintaining the loudspeaker circuit operative when theoperation of the shaft is controlled by said nger piece.

l1. In a radio signal receiving system, a radio receiver having at leastone tuning element, a motor for operating said tuning element, means atsaid motor including a plurality of conductors for selectivelycontrolling the operation of said motor to predetermined andnon-predetermined positions, selectively operable circuit-controllingmeans for including desired ones of said conductors in an operatingcircuit for said motor, a remote control station, other conductorsconnecting said remote control station and said selectively operablecircuit-controlling means, mechanism at said remote control station forincludingsaidlastmentioned conductors in a circuit to selectively governthe operation of said circuit-controlling means to operate said motor toa predetermined position, and means at said remote control station foroperating' said motor at will to any desired position.

l2. In a radio signal receiving system, a radio receiver having at leastone tuning element, a motor for operating said tuning element, means atsaid motor including a plurality of conductors for selectivelycontrolling the operation of said motor to predetermined andnon-predetermined positions, a progressively movable switch forincluding desired ones of said conductors in an operating circuit forsaid motor, a remote control station, other conductors connecting saidremote control station and said progressively movable switch, mechanismat said remote control station for including said last-mentionedconductors in a circuit to selectively govern the operation of saidprogressively movable switch to operate said motor to predeterminedpositions, and means at said remote control station for operating saidmotor at will to any desired position.

13. In a radio signal receiving system, a radio receiver having at leastone tuning element, a motor for operating said tuning element, means atsaid motor including a plurality of conductors for selectivelycontrolling the operation of said motor, one of said conductors beingprovided for each desired position of adjustment of said element, aprogressively movable switch for completing a circuit for said motorincluding one of said conductors, a remote control station, conductorsconnecting said remote control station and said progressively movabieswitch, and mechanism inoluding a plurality of keys at said remotecontrol station for selectively extending said conductors terminating atsaid remote control station to complete a circuit for directivelyoperating said progressively movable switch.

ADOLPH A. THOMAS.

